This is guide how to install CyanogenMod 10 on your T-Mobile Galaxy S3 but first do keep in mind that you have installed ClockworkMod recovery and backup all data.
steps to install Android 4.1 Jelly Bean on T-Mobile Galaxy S3 :
- Get the ROM from here ( more XDA LINK) and Google Apps package from here (gapps-jb.1.zip).
- Copy both downloaded files into internal SD card of device, don’t place under external SD card.
- Turn the device off and put the device in recovery, to do so reboot the device by holing down Volume Up,Home and then the Power buttons together until the screen turns on
- Once you’re in recovery, make an android backup of your current ROM that will allow you to go back to original ROM
- Perform full wipe, first select the wipe data/factory reset, and confirm on the next screen.
- Select “Install Zip from SD Card” then “Choose Zip from SD Card” and locate the downloaded file thatyou’ve transferred in above step and confirm installation. Wait till installation complete.
- Repeat the step 6 and install Google Apps.
- Once the installation is completed, select “Go Back” after that select “Reboot System Now.”
Congratulation!!, you'r have been install Android Jelly Bean on T-Mobile Galaxy S3